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• The spin-dependent electronic transport properties of zigzag phosphorene nanoribbons (ZPNRs);. • The electronic transport through the ZPNRs shows apparent spin polarization;. • The spin polarization is tightly dependent on the absorbing manners;. • Negative differential resistance characteristic can be observed on current-voltage curves. Based on density functional theory (DFT) and non-equilibrium Green's function (NEGF) method, we have investigated spin-dependent electronic transport properties of zigzag phosphorene nanoribbons (ZPNRs) coupled with chromium triiodide (CrI 3) molecules. Three different adsorption models have been considered: CrI 3 molecule is placed on ZPNR surface (C-type), and CrI 3 molecule is lateral adsorbed on the edge of ZPNR with its molecule panel vertical (V-type) or parallel (P-type). We discovered that ZPNR's electrical transport clearly displays spin polarization, owing to the coupling between ZPNR and CrI 3 molecules. And spin-polarization is tightly dependent on the absorbing manners. Moreover, the negative differential resistance (NDR) characteristics can be observed from current-voltage curves and modulated by absorbing molecules. Furthermore, we also discovered that CrI 3 is vertically adsorbed on the surface of the ZPNRs has a better spin-polarization efficiency than the other two cases. [ABSTRACT FROM AUTHOR]

The spin polarization of current plays an important role in the performance of spintronic devices. Therefore, a highly spin-polarized current source has always been explored through various methods. We study the effects of magnetic order on the electronic structures of antiferromagnetic (AFM) MnBi 2 Te 4 films. A significant spin splitting is found in the surface states of a AFM MnBi 2 Te 4 film with three septuple layers (SLs). The AFM film can show typical metallic behavior for spin-down electrons, and exhibit a semiconductor or insulator behavior with a band gap at the Fermi level for spin-up electrons, just like semimetal ferromagnets with theoretical spin polarization up to 100%. We also study that the electron transport in the 3-SLs AFM film with a square potential barrier, we find a highly spin-polarized current can be switched on and off by modulating the barrier height in the film. • 3-SLs AFM film exhibits a semimetal ferromagnets behavior. • A highly spin-polarized current can be switched on and off by modulating the barrier height. • Gapless surface states induced by magnetic order. • Large spin splitting in spin splitting. [ABSTRACT FROM AUTHOR]

• Different edge hydrogenations realize the transition of β -SiC 7 nanoribbons from semiconductors to half-metals to metals. • Spatially separated edge states lead to, arbitrary pairings of upper and lower edge hybridizations are able to diversify the bands near the Fermi level. • The heterojunction H H-zSiC 7 NR-2H H possesses good dual spin filtering properties at low bias and exhibits the NDR phenomenon. Atomic capping is a common approach in edge modification to tune band engineering and can be achieved experimentally through hydrogen plasma etching. Based on first-principles calculations, nine symmetric and asymmetric structures are constructed with different numbers of hydrogen atoms passivated at the edge of β -SiC 7 nanoribbons. An in-depth study reveals that different edge hydrogenations realize the transition from semiconductors to half-metals to metals, firstly, because different numbers of hydrogen atoms lead to different edge atomic orbital hybridizations, and, more importantly and specifically, because the bands around the Fermi level of β -SiC 7 nanoribbons are all derived from the spatially separated edge states, so that arbitrary pairings of upper and lower edge hybridizations are able to diversify the bands near the Fermi level and bring about a richer electronic properties. We also design the metallic H-zSiC 7 NR-H and semiconducting 2H-zSiC 7 NR-H into a heterojunction, which possesses good dual spin filtering properties at low bias, can achieve a spin polarization transition from -100 % to 100 %, and exhibits the NDR phenomenon. These findings suggest that β -SiC 7 nanoribbons have promising applications in the field of spintronics. [ABSTRACT FROM AUTHOR]

• The magnetism of LaFe x Ni 1- x O 3 are investigated based on the first principles. • A detail discussion of magnetic performance of FM and AFM in LaFe x Ni 1- x O 3 system. • LaFe x Ni 1- x O 3 undergoes a magnetic transition from FM to AFM when x increases to 0.5. • The magnetic moment of O atom increases with the increase of Fe doping concentration. The effect of different Fe doping concentration (x = 0.125, 0.25, 0.375 and 0.5) on electronic structure and magnetic properties of LaNiO 3 (LNO) have been performed on the spin polarization calculations based on first principles. The calculation results show that with the increase of Fe dopant concentration, LaFe x Ni 1- x O 3 undergoes a magnetic transition from ferromagnetism (FM) to antiferromagnetism (AFM). The net magnetic moments of LaFe 0.125 Ni 0.875 O 3 , LaFe 0.25 Ni 0.75 O 3 , LaFe 0.375 Ni 0.625 O 3 and LaFe 0.5 Ni 0.5 O 3 in the FM ground state are found to be 12.00 µ B /supercell, 16.00 µ B /supercell, 20.06 µ B /supercell and 23.96 µ B /supercell, respectively. In the magnetic configuration of AFM of LaFe x Ni 1- x O 3 (x = 0.125 and 0.375) with the nearest doping position, the asymmetric magnetic structure leads to the symmetry of the spin-ordered AFM network is broken, resulting in the generation of net magnetic moment of -3.06 µ B and 3.87 µ B. The net magnetic moment in LaFe x Ni 1- x O 3 mainly originates from transition metals (TM) Fe, Ni and magnetized O atoms. [ABSTRACT FROM AUTHOR]

The compressibility was calculated of electrons as a function of external magnetic, temperature and carrier density in the parabolic lateral barrier quantum wires (QWRs). The compressibility found by using Seitz's theorem in which electron self-energy is calculated within the random-phase approximation. All results for GaAs QWRs show that a large difference between the compressibility in low- and high-temperature region at external magnetic fields. These results can help clarify how the Coulomb interaction and exchange, correlation energy affect the compressibility of the semiconductor across a wide range of density, temperature, and external magnetic. • Spin, temperature, and carrier density dependence of electron compressibility in quantum wires is analyzed. • Compressibility increases with external magnetic and temperature. • Compressibility has a clear minimum at low every external magnetic an at low carrier density below 1*106 cm−1. • The results are consistent with experimental results. [ABSTRACT FROM AUTHOR]

In degenerate quantum plasma the energy behavior of electrostatic modes propagating perpendicular to the external magnetic field is studied by employing the separated spin evolution quantum hydrodynamic (SSE-QHD) model. This model reveals that spin electron cyclotron wave (SECW) appears additionally with the upper hybrid wave (UHW). In case of SECW, the curves for the energy flow speed at different levels of spin polarization effect flip over at a particular value of wave number. The spin polarization effect enhances the energy flow speed before this value of wave number and then suppresses it afterward. The energy flow speed is enhanced by spin polarization effect in the entire range of wave number for the propagation of UHW. The Bohm potential effect drastically increases the energy flow speed at high wave number domain in both the waves. This study may find its applications to understand the energy behavior inspin polarized solid state plasmas • Studied the energy flow speed for the propagation spin electron cyclotron wave (SECW) and upper hybrid wave. • Examined how the spin polarization and Bohm potential influence the energy flow speed. • Results are applicable to environments like solid state plasma. [ABSTRACT FROM AUTHOR]

We study the spin transport in bilayer graphene nanoribbons (BGNs) in the presence of Rashba spin-orbit interaction (SOI) and external gate voltages. It is found that the spin polarization can be significantly enhanced by the interlayer asymmetry or longitudinal mirror asymmetry produced by external gate voltages. Rashba SOI alone in BGNs can only generate current with spin polarization along the in-plane y direction, but the polarization components can be found along the x, y and z directions when a gate voltage is applied. High spin polarization with flexible orientation is obtained in the proposed device. Our findings shed new light on the generation of highly spin-polarized current in BGNs without external magnetic fields, which could have useful applications in spintronics device design. • Investigate the spin polarized transport properties in bilayer graphene nanoribbons in the presence of Rashba spin-orbit interaction. • Spin polarization can be significantly enhanced by the interlayer asymmetry or longitudinal mirror asymmetry produced by external gate voltages. • Spin current with high spin polarization and high flexibility in the orientation can be obtained in the proposed device. • The proposed device could have useful applications in spintronics. [ABSTRACT FROM AUTHOR]

The property of matter-wave vector solitons in a spin-1 Bose-Einstein condensate with spin-orbit and Zeeman couplings is investigated by multiscale perturbation method. The excitation spectrum and the corresponding state vectors of the system are obtained analytically, and they can be adjusted by the parameters of the system. The bright and dark vector solitons are formulated by reducing the three-component coupled Gross-Pitaeviskii equations to a standard nonlinear Schrödinger equation, which has the solutions of the bright and dark solitons with positive or negative mass depending on the product of the effective dispersive and nonlinear coefficients. The moving vector solitons are demonstrated by adjusting specific momentum near the energy minimum. Finally, the magnetized features of the vector solitons are discussed by the spin polarization of the system. • The excitation spectrum for the vector solitons, determined by the parameters of the system, is obtained analytically. • The analytical bright and dark vector solitons are formulated and the moving solitons are demonstrated by adjusting specific momentum. • The solitons with positive or negative mass depending on the product of the effective dispersive and nonlinear coefficients are analyzed. • The magnetized features affected by spin-orbit and Zeeman couplings are discussed by the spin polarization of the system. [ABSTRACT FROM AUTHOR]

Spin dependent transport in one-dimensional four-terminal rings (FTRs) is investigated in the presence of the Rashba spin-orbit coupling (RSOC). In the absence of the RSOC, the conductances as a function of the electron wave vector show resonant behavior for symmetrical configurations. For asymmetrical configurations, the conductances show peculiar zero-conductance resonances, and two kinds of conductance zeros have been found. In the presence of the RSOC, the original conductance zeros disappear as new conductance zeros are generated. Moreover, two kinds of symmetry relations have been found in the conductances, the spin dependent conductances and the spin polarizations. For the FTRs with axial or central symmetry, the phase-locking effect has been found in terminal 2, where there is no spin polarization. Under a weak magnetic field, the Zeeman term is treated by a perturbation, and it is found that the Zeeman effect is obvious for weak RSOC. • The transmission coefficients for the four-terminal rings (FTRs) are derived analytically. • Two kinds of conductance zeros have been found in the conductances. • The phase-locking effect has been found in terminal 2 for the FTRs with axial or central symmetry. • The results are extended to the case of a weak magnetic perturbation. [ABSTRACT FROM AUTHOR]

We calculated the electronic structure, magnetism and optical properties of the Sc-doped, Y-doped, and (Sc, Y)-codoped anatase TiO 2 (101) surface using a projector augmented wave (PAW) method with GGA + U approximation. Sixteen doping systems were considered in the present work. The lattice distortion results in the generation of an internal local electric field. In addition, the difference between positive and negative spin charge densities leads to the generation of magnetism. With the exception of the Sc@in2 system, the width of band gap of the other doping systems increases to varying degrees, leading to a blueshift of the absorption edge. The photocatalytic activity of all the doping systems was improved to different degrees. The absorption intensity and absorption range of the Sc@in2&Y@O13 system in the visible-light region is the highest amongst all doping systems. This mainly attributed to the formation of hole states and the presence of impurity bands. • Lattice distortion can result in the generation of local electric fields. • The Sc@Ti5&Y&Ti6 mainly induce polarization of O-2p spin electrons and less induce polarization of Ti-3d spin electrons. • Except for Sc@in2, the width of band gap of the other doping systems increases to varying degrees. • The absorption intensity and absorption range of Sc@in2&Y@O13 is the highest amongst all doping systems. [ABSTRACT FROM AUTHOR]

This work presents a theoretical investigation on the electronic properties of double atomic carbon chains bridging graphene electrodes with density functional theory in combination with non-equilibrium Green's function. The influence of strain on the conductance of atomic carbon chains is significant. However, the coupling effect between adjacent chains dominates the intrinsic transport of double atomic carbon chains. For the coupled double atomic chains, the electron conductance of even-numbered atomic chains is significantly enhanced, while the electron conductance of odd-numbered atomic chains decreases to a certain degree, and the dependence of the conductance of double atomic chains on electrode configuration is stronger than the corresponding single atomic chain. More intriguingly, the coupled double atomic chains exhibit excellent spin-filtering properties with antiparallel spins on two electrodes. The current spin polarization stems from the coupling-induced changes of electron density and band offset reaches 100%. The coupled double atomic carbon chains have great potential application in spintronic devices and carbon-based field-effect transistors. • Coupling of carbon atomic chains increase the average conductance of atomic chains. • Coupling of carbon atomic chains induces very strong spin filter effect, even reaches 100%. • MR ratios of double carbon atomic chains increase by up to 5 orders of magnitude of the single carbon atomic chain. [ABSTRACT FROM AUTHOR]

The electron effective mass in GaAs quantum wires has been estimated by using a full dynamical random-phase approximation to examine its properties versus spin polarization, temperature, and carrier density. A decrease of mass with spin polarization is seen. The minority mass increases with the polarization while the majority mass decreases and this behaviour is seen for all densities. A maximal enhancement of mass at moderate temperature around 25 K is also presented. These calculations show a qualitative consistence with results in two-dimensional systems and help to control the electronic transport in quantum wires. • Spin and temperature dependence of quantum wire is analyzed. • Majority mass increases with spin polarization while minority mass decreases. • Majority mass is significantly enhanced below 50 K and peaks at 25 K. • Consistent results with two-dimensional values are seen. [ABSTRACT FROM AUTHOR]

Abstract We have constructed an analytic formula to treat the perpendicular magnetic anisotropy energy in ferromagnetic metals with low symmetry, such as C 4 V and C 3 V. We find that the anisotropy energy is proportional to a part of the expectation values of the orbital angular momentum and magnetic dipole operator. Although the result is similar to the model proposed by Laan (1998) [2] , we have derived a concrete expression for the spin-flip virtual excitation process term, which can be dominant in atoms with small magnetic moments and/or small exchange splitting. Pt monatomic layer with proximity-induced spin polarization grown on Fe is an example of this. Other multilayer systems such as Co/Pd and Co/Ni, and bilayer systems such as Fe(CoB)/MgO can be discussed similarly. Moreover, the relation between perpendicular magnetic anisotropy energy and measurable physical parameters is discussed based on X-ray magnetic circular dichroism spectroscopy. Highlights • An analytic formula to treat the perpendicular magnetic anisotropy energy in ferromagnetic metals with low symmetry has been constructed. • We find that the anisotropy energy is proportional to a part of the expectation values of the orbital angular momentum and magnetic dipole operator. • We have derived a concrete expression for the spin-flip virtual excitation process term. [ABSTRACT FROM AUTHOR]

Highlights • The Fe doped SnS 2 system exhibits multiple spin-resolved transport properties of negative differential resistance and large TMR. • Near 100% spin polarization was realized in the parallel spin configuration. • 104 magnitude of TMR has been realized under a wide bias window. • The spin down d states of Fe near E F is the essential reason of the NDR behavior and large TMR. Abstract In this work, the spin-resolved transport properties of the Fe doped SnS 2 monolayer devices have been investigated. The results show that the doping systems have the transport properties of negative differential resistance, large magnetoresistance effect and near 100% spin polarization effect when the magnetization directions of two electrodes are in parallel. Moreover, the mechanisms for the properties also have been discussed. The original reason of these results could be due to the half-metallic of the doping system. Our results imply that Fe doped SnS 2 monolayer is a promising candidate for the future spintronic devices. [ABSTRACT FROM AUTHOR]

Highlights • The spin-polarized transport in zigzag silicene nanosystem is studied. • The spin polarization can reach almost 100% by applying circular polarized light. • The spin-polarized transport is robust against the size change of the nanosystem. Abstract We study the spin-polarized transport induced by photoirradiation in zigzag silicene nanosystem, based on tight-binding approach, Green's function method and Landauer–Büttiker formula. By applying strong circular polarized light, silicene nanosystem can be transformed into a quantum Hall insulator, where the spin-down subband is gapped while the spin-up subband persists gapless edge state. Therefore, the dc conductance is dominated by the spin-up electrons, and the spin polarization can reach almost 100% around the Fermi energy. The spatial-resolved local density of states confirm that the spin-up electrons transport at two edges of the nanosystem in opposite current directions. Furthermore, because of the topological origin of the edge state, the spin-polarized transport is very robust against the size change of the nanosystem. [ABSTRACT FROM AUTHOR]

Abstract Based on first principles calculation method, we design and investigate the spin transport properties of two type heterostructures based on zigzag silicene nanoribbons (ZSiNRs). The first one consists of hydrogen-terminated ZSiNR (ZSiNR-H) and Rx-terminated ZSiNR (ZSiNR-Rx), here, Rx = O, S, P. The rectification behavior can be observed for heterostructures consisting of ZSiNR-H and ZSiNR-O (ZSiNR-S). The second one can be fabricated with a ZSiNR-Rx central scatter region between two ZSiNR-H electrodes. The results show that this device could maintain its good spin filtering effect for ZSiNR-O model in parallel (P) and antiparallel (AP) spin configuration with large bias range. Then we further investigate the spin-dependent transport with various length of ZSiNR-O region, and find that better spin filtering effect (near 100% spin polarization) can be observed for longer ZSiNR-O region. ZSiNR-S model show analogous spin filtering effect. However, neither rectification behavior nor spin filtering effect arise for ZSiNR-P models. Highlights • The constructure of two type heterostructures. • ZSiNR-O (ZSiNR-S) heterostructures show spin filtering effect or rectification behavior. • Neither rectification behavior nor spin filtering effect arise for ZSiNR-P models. [ABSTRACT FROM AUTHOR]

We have studied the partially spin polarized fractional quantum Hall states using Chern Simon's theory and plasma picture proposed by Halperin. Using these theoretical techniques we have tried to find the stable polarized states of different filling fractions observed in experiments. We have calculated the ground state energies of those states and also pair correlation function. We have described the nature of the states by the behaviour of this quantity. In our study, we have seen that the partially polarized states, which do not fit with Jain's composite fermion description are basically the mixed state of up-spin liquid phase and down-spin solid phase. [ABSTRACT FROM AUTHOR]

Spin transport properties in a non-uniform quantum wire (QW) in the presence of both the Rashba and Dresselhaus spin–orbit couplings (SOCs) is investigated by using the non-equilibrium Green's function (NEGF) method combined with the Landauer Büttiker formalism. It is found that such a non-uniform quantum wire exhibits considerable spin polarization in its conductance in the influence of both the Rashba and Dresselhaus SOCs, and that the two SOCs' strengths strongly affect both the magnitude and sign of the electron spin polarization. Interestingly, the Rashba and Dresselhaus SOCs play the same modulating role in the electron spin polarization. The proposed nanostructure can potentially be utilized to devise an all-electrical spintronic device. [ABSTRACT FROM AUTHOR]

The dwell time is calculated for electron in a novel magnetic nanostructure with zero average magnetic fields, which is realized experimentally by constructing three nanosized ferromagnetic stripes on top and bottom of the InAs/Al x In 1-x As heterostructure. Although structural magnetic fields are averagely equal to naught, the dwell time is still dependent on electron spins owing to the spin-field interaction. Due to the dependence of effective potential experienced by electron on structural parameters (such as magnetic strength and device width), spin-polarized dwell time can be conveniently modulated by reasonably fabricating ferromagnetic stripes. As a result, this novel magnetic microstructure can act as a temporal electron-spin splitter for spintronic device applications. • Dwell time is calculated for electron in a novel SMQM. • Dwell time still depends on electron spins in spite of zero average magnetic field. • Spin-dependent dwell time is manipulated by incident angle, magnetic strength and structural width. • A temporal spin splitter is achieved for spintronics device applications. [ABSTRACT FROM AUTHOR]

Using the tight-binding formalism, we explore the effect of weak disorder upon the conductance of zigzag edge silicene nanoribbons (SiNRs), in the limit of phase-coherent transport. We find that the fashion of the conductance varies with disorder, and depends strongly on the type of disorder. Conductance dips are observed at the Van Hove singularities, owing to quasilocalized states existing in surface disordered SiNRs. A conductance gap is observed around the Fermi energy for both edge and surface disordered SiNRs, because edge states are localized. The average conductance of the disordered SiNRs decreases exponentially with the increase of disorder, and finally tends to disappear. The near-perfect spin polarization can be realized in SiNRs with a weak edge or surface disorder, and also can be attained by both the local electric field and the exchange field. [ABSTRACT FROM AUTHOR]

Carrier recombination and electron spin relaxation dynamics in asymmetric n-doped (110) GaAs/AlGaAs quantum wells are investigated with time-resolved pump-probe spectroscopy. The experiment results reveal that the measured carrier recombination time depends strongly on the polarization of pump pulse. With the same pump photon flux densities, the recombination time of spin-polarized carriers is always longer than that of the spin-balanced carriers except at low pump photon flux densities, this anomaly originates from the polarization-sensitive nonlinear absorption effect. Differing from the traditional views, in the low carrier density regime, the D'yakonov–Perel' (DP) mechanism can be more important than the Bir–Aronov–Pikus (BAP) mechanism, since the DP mechanism takes effect, the spin relaxation time in (110) GaAs QWs is shortened obviously via asymmetric doping. [ABSTRACT FROM AUTHOR]

We study the spin-dependent tunneling time, including group delay and dwell time, in a graphene based asymmetrical barrier with Rashba spin–orbit interaction in the presence of strain, sandwiched between two normal leads. We find that the spin-dependent tunneling time can be efficiently tuned by the barrier width, and the bias voltage. Moreover, for the zigzag direction strain although the oscillation period of the dwell time does not change, the oscillation amplitude increases by increasing the incident electron angle. It is found that for the armchair direction strain unlike the zigzag direction the group delay time at the normal incidence depends on the spin state of electrons and Hartman effect can be observed. In addition, for the armchair direction strain the spin polarization increases with increasing the RSOI strength and the bias voltage. The magnitude and sign of spin polarization can be manipulated by strain. In particular, by applying an external electric field the efficiency of the spin polarization is improved significantly in strained graphene, and a fully spin-polarized current is generated. [ABSTRACT FROM AUTHOR]

The spin-polarized transport properties of multiterminal silicene nanodevices are studied using the tight binding model and Landauer–Buttier approach. We propose a four-terminal †-shaped junction device and two types of three-terminal T-shaped junction devices, which are made of the crossing of a zigzag and an armchair silicene nanoribbon. If the electrons are injected into the metallic lead, the near-perfect spin polarization with 100% around the Fermi energy can be achieved easily at the other semiconducting leads. Thus the multiterminal silicene nanodevices can act as controllable spin filters. [ABSTRACT FROM AUTHOR]

By employing the separated spin evolution quantum hydrodynamic model, non-linear evolution of obliquely propagating spin electron acoustic wave (SEAW) is presented. The solitary structures of SEAW is investigated through the Korteweg–de Vries (KdV) equation derived using reductive perturbation method. From the first order perturbations we derive the dispersion relation of SEAW and find that both the spin polarization and the propagation angle reduce the phase velocity while the electron streaming enhances it. Using small amplitude approximation, the solitary structure of SEAW is analyzed and the effects of spin polarization, propagation angle and electron streaming on the SEA soliton are studied. Our numerical results demonstrate that the spin polarization and the propagation angle play a balancing act on the soliton structures. The possible applications of our investigation to the astrophysical environments like white dwarfs is also discussed. [ABSTRACT FROM AUTHOR]

The mechanical, structural, electronic and magnetic properties of s -triazine sheet ( C 6 N 6 ) with embedded Mn atom ( Mn – C 6 N 6 ) is investigated under the influence of external environment (symmetric deformation and perpendicular electric field) using density-functional theory (DFT) with the spin polarized generalized gradient approximation (GGA) and Hubbard U correction ( GGA + U ). Our results show that Mn – C 6 N 6 system is structurally and mechanically stable. The binding energy of Mn embedded in C 6 N 6 sheet can be modulated under the influence of external environment. Moreover, the semiconducting and magnetic properties of the Mn – C 6 N 6 systems under external fields are preserved. We also explore the geometries, electronic and magnetic properties of Mn – C 6 N 6 with adsorbed atoms and molecules. The Mn – C 6 N 6 with adsorbed O atom and O 2 molecule systems shows half-metallic character whereas the remaining systems preserve their semiconducting property. The total magnetic moment per unit cell in most of the systems is found to reduce as compared to that of the Mn – C 6 N 6 sheet. The reduction in the magnetic moment can be related to the strong interactions among the Mn atom and the surrounding atoms which lead to the formation of low-spin configurations. Overall, our results indicate that the Mn – C 6 N 6 systems with and without adsorbed atoms and molecules can serve as potential candidates for future spintronics and catalysis applications. [ABSTRACT FROM AUTHOR]

Three-dimensional Dirac semimetal is an ideal platform in studying topological phase transitions due to its exotic electronic structure. Based on the effective Hamiltonian of material Na 3 Bi where two degenerated Dirac points are constructed by four Weyl nodes and protected by crystal symmetry, we study its Floquet phase transitions induced by circularly polarized light in off-resonant limit. By breaking the time-reversal symmetry and taking the quadratic momentum into account, abundant phases are realized, including Weyl semimetal, spin-polarized Weyl semimetal (SP-WSM), and normal insulator. The SP-WSM phase is a new phase, in which only pairs of spin-up (or spin-down) opposite-chirality Weyl nodes are remained while the other pairs of spin-down (or spin-up) opposite-chirality Weyl nodes are eliminated. Importantly, all the phase transitions can be manipulated not only by tuning the light intensity but also by changing the incident direction of light. To understand them, we have in detail analyzed the trajectory of Weyl nodes in k space controlled by the circularly polarized light and manifested them with the angle- and spin- dependent Hall conductivity. [ABSTRACT FROM AUTHOR]

First principles investigations are performed on understanding the spin-polarized transport in carbon nanotubes and carbon nanotube bundles consisting of ( 8 , 0 ) and ( 17 , 0 ) SWCNTs kept in vertical (out-of-plane) arrangement and contacted by two CrO 2 Half-Metallic-Ferromagnetic (HMF) electrodes. On comparison of the results for all the structures, it is observed that carbon nanotube bundle consisting of ( 17 , 0 ) CNT offers high TMR ∼100% and the transport phenomenon is tunneling, since there are no transmission states near Fermi level. However, in individual ( 8 , 0 ) and ( 17 , 0 ) CNT the transport is not because of tunneling, since there are significant number of transmission states near Fermi level. High Magneto Resistance (MR) 96% and 99% is observed in individual ( 8 , 0 ) and ( 17 , 0 ) CNTs respectively. Both TMR and Spin Injection Efficiency η (Spin-Filtration) are higher in ( 17 , 0 ) carbon nanotube bundle structure, which is due to carbon nanotube bundle acting as a perfect barrier in vertical (out-of-plane) arrangement resulting in negligible spin-down current ( I ↓) in both Parallel Configuration (PC) and Antiparallel Configuration (APC). [ABSTRACT FROM AUTHOR]

Here, the spin transport properties of molecular devices comprised of a transition metal-dibenzotetraaza[14]annulene complex (TM-DBTAA, TM=Co, Cu, Ni) connected to two single-walled carbon nanotube (SWCNT) electrodes have been theoretically investigated by using the first-principles method. In addition, the effect of O 2 adsorption on the TM atom on the spin transport properties of the investigated devices is inspected. The calculations reveal that Co-DBTAA behaves as a spin filter with SFE close to 100%. Upon O 2 adsorption, the spin polarization of the current for Co-DBTAA is changed from spin-down to spin-up with the magnitude of SFE nearly unchanged. More interestingly, for the spin non-polarized and nonconducting Ni-DBTAA, the adsorption of an O 2 molecule induces a spin-up polarized current with remarkable SFE larger than 90%. This work is helpful for future designing of molecular spin filters as well as gas sensors. • Co-DBTAA has a spin filtering efficiency close to 100%. • The polarization of spin filtering in Co-DBTAA is reversed by oxygen adsorption. • Ni-DBTAA is spin non-polarized and nonconducting. • Oxygen adsorption induces a large spin filtering efficiency in Ni-DBTAA. [ABSTRACT FROM AUTHOR]

By combining the density functional theory with non-equilibrium Green's function method, we theoretically design and investigate the spin-dependent transport properties of two molecular magnetic tunnel junctions (MMTJs) with the AsFNRs embedded in zigzag graphene nanoribbons in parallel and antiparallel spin configurations. The findings reveal that the MMTJs have distinct transport characteristics depending upon the orientations of the AsFNRs. Changing the spin configurations leads to two different net spin currents, and the maximal order of the tunneling magnetoresistance magnitude can reach 10 7 %. In addition, a negative differential resistance (NDR) effect is found in our MMTJs. Our findings provide suitable candidates of MMTJs for the future spintronic devices. • We study spin-dependent transport in molecular magnetic tunnel junctions (MMTJs) with AsFNRs. • It shows that MMTJs have distinct transport properties depending on the orientations of AsFNRs. • Changing spin configurations leads to different spin currents, with maximal tunneling magnetoresistance being 107%. • The negative differential resistance effect is found in our MMTJs. • Our findings provide suitable candidates of MMTJs for future spintronic devices. [ABSTRACT FROM AUTHOR]

We examine the collective spin-polarized density motion in an unmagnetized plasma under a high frequency electromagnetic (EM) wave modulation. Spin effect in a quantum plasma is considered for the first time at a finite temperature near the Fermi temperature with considering collisional damping. A nonlinear two-fluid spin quantum magnetohydrodynamic model is used and solved self-consistently. The nonlinear effect and the reducing g -factor enhance the spin-polarization, while the collisional damping decreases the spin polarization. Strong spin-polarization is derived and the contribution of the spin-polarized current to the EM wave is much larger than that of the classical current. [ABSTRACT FROM AUTHOR]

We use nonequilibrium Green function to analyze the nonequilibrium spin-polarized thermal transport through the ferromagnetic–quantum dot–metal system, in which a quantum dot (QD) is coupled to the ferromagnetic and metal electrodes with the voltage bias and the temperature shift. The differential thermoelectric conductance L ( θ ) is always zero and has no relation with the temperature shift when ε is equal to the Fermi level. The positive and negative values of L ( θ ) manifest the thermoelectric characteristic of electron-like (or hole-like) carrier when the temperature shift is nonzero. The electrostatic potential U becomes spin-dependent, and makes the dot level renormalization when the ferromagnetic–quantum dot–metal system is driven by the voltage bias and the temperature shift. We define that the spin polarization of the currents between the spin current I s and the electric current I c is denoted as I s / I c . The spin polarization I s / I c shows novel and unique physical phenomenon when the voltage bias and the temperature shift are changed in the nonequilibrium state. Another interesting phenomenon is that we can obtain the pure spin current and a zero point of the thermocurrent I t h by adjusting the voltage bias and the temperature shift. [ABSTRACT FROM AUTHOR]

We discuss the localization and spin dynamics of tunable spin-orbit coupled Bose-Einstein condensates in deep optical lattices. Rich localized phenomena (breather, soliton, self-trapping, and diffusion) are observed. The critical conditions for occurring different localized states are obtained analytically and confirmed numerically. Under the critical conditions, we observe localized states with fixed initial spin polarization. When the critical condition is not satisfied, because of spin-momentum locking, quenching of Raman coupling from soliton state excites spin dynamics. If initially the soliton is in a nearly unpolarized (polarized) state, persistent (damped) spin dynamics is excited. The system finally transforms to a new polarized state in the damped spin dynamics. The localization and spin dynamics can be well controlled by periodic modulation of Raman coupling. • Localization and spin dynamics of tunable SOC BECs in deep optical lattices are studied. • Rich localized states (breather, soliton, and self-trapping) with fixed spin polarization are predicted. • The critical conditions distinguish different localized states are obtained analytically. • Persistent (damped) spin dynamics is excited by quenching Raman coupling from soliton state. • We provide a way for manipulating the localization and spin dynamics in SOC BECs. [ABSTRACT FROM AUTHOR]

The skyrmion Hall effect has been regarded as a critical issue in skyrmion future applications, which indicates that it causes skyrmions to deviate from the direction of the driving force and leads to the destruction of skyrmion at the sample edge. In the meanwhile, perpendicular magnetic anisotropy is a promising method to manipulate the skyrmion motion by adding a material with high crystalline anisotropy into an existing material. It has been also investigated that spin polarization angles also have an influence on the skyrmion motion directions. Here, we statistically study a bilayer nanostructure, where the skyrmion Hall effect would be eliminated by modifying perpendicular magnetic anisotropy coefficients and spin polarization angles. Our results may provide a useful method for the design of skyrmion based spintronics devices without skyrmion Hall effect, to meet the need for future high-density information storage applications. • Skyrmion based spintronics devices without SkHE. • SkHE elimination by tuning PMA coefficients and spin polarization angles. • Two PMA coefficients' areas. [ABSTRACT FROM AUTHOR]

• Magnetoresistance can change from positive to negative with a measurable conductance. • Magnetoresistance and critical points can be manipulated by the potential and exchange field. • Negative magnetoresistance is a signature of spin polarization. • Positive and negative magnetoresistance still survives under finite temperature and disorder. • A spin-valley filter can also be realized by the potential in the proposed junction. Electrical manipulation of transition metal dichalcogenides is very important to develop spintronics and valleytronics. We theoretically study the electron transport through a ferromagnetic/ferromagnetic insulating/ferromagnetic WSe 2 tunnel junction. It is found that the tunneling magnetoresistance (TMR) could change from positive to negative values with a measurable conductance. The prominent positive and negative TMR with wide parameter regimes can be achieved and manipulated by the potential and exchange field. The negative TMR behavior could be regarded as a signature of spin polarization, since the conductance is always spin-polarized when the negative TMR occurs. The positive and negative TMR still survives under finite temperature and disorder. Furthermore, a spin-valley filter can also be realized in the proposed junction. The results suggest an electrical control of the ferromagnetic WSe 2 junction. [ABSTRACT FROM AUTHOR]

Using the spin-polarized density functional theory (DFT) and the DFT + U method, the geometric and electronic properties of the hematite α –Fe 2 O 3 (0001) film with the sulfur (S) atom doping and adsorption have been investigated systematically. The most stable hematite α –Fe 2 O 3 (0001) film with an anti-ferromagnetic arrangement is identified. For the study of sulfur adsorption on the film, the S adatom prefers to bond with three O atoms, in the center of a triangle formed by the three O atoms. The S acts as a cation at this site. The sulfur adsorption has introduced two gap states, in addition to the unoccupied surface states. Furthermore, with the most stable S-adsorption configuration, the diffusion of the S adatom from the surface to the inside is searched and the transition state along the minimum-energy pathway is also evaluated. For S-doping in the film, it is found that S substitution of O in the top layer is energetically favored than that in the deeper layer. It shows that the value of the band gap is reduced to ∼1.26 eV from ∼1.43 eV of the clean film. The formation energy of S substitution of O in the film is also obtained. [ABSTRACT FROM AUTHOR]

The electron tunneling through a nonmagnetic heterostructure modulated by both the in-plane magnetic field and the δ -doping has been investigated in detail using the transfer-matrix method. The numerical results indicate that, in such a nonmagnetic device, one can obtain the considerable spin polarization which is dependent on the in-plane magnetic field and the δ -doping as well as the wave vector in the plane of the barrier. Thus, we can design the spintronic devices based on nonmagnetic heterostructures controlled by the in-plane magnetic field and the δ -doping as well as the wave vector. [ABSTRACT FROM AUTHOR]

Sr 2 CrOsO 6 double perovskite (DP) has been gaining importance in recent years thanks to its high ordering temperature ( T c = 725 K ) that is the highest T c measured among all DPs so far. Spin-polarized (5d t 2g )-orbital of Os-atoms is completely filled, which allows the compound to be considered as fully spin-polarized exactly at the limit of the metal–insulator transition. This interesting property gives the compound exceptional properties and more ability to use in spintronic applications. In this paper, the energetic and the magnetic behavior of this material have been explored using Monte Carlo Simulation (MCS) within the framework of Ising model. Ground state phase diagram has been dressed and analyzed. Size effect on the magnetic properties has been analyzed. Effect of the crystal field of Osmium on the thermal behavior has been explored. Critical exponents have been calculated, discussed regarding the crystal field of Osmium and evaluated against the universality class. [ABSTRACT FROM AUTHOR]

We study the possibility to control the spin polarization and spin-dependent transport in a graphene sheet by considering a ferromagnetic layer in the presence of the Rashba spin–orbit interaction. Studying the scattering problem with the help of the Green function (which was found explicitly), we obtained simple analytical expressions for the spin dependent transmission probability. Using the small exchange parameter and Rashba coupling constant, we can obtain any degree of spin polarization, but in the case of a small interaction region, only for slow electrons. [ABSTRACT FROM AUTHOR]

We theoretically investigate the spin-dependent thermoelectric effects in a quantum dot that is connected with a normal metal lead and a ferromagnetic metal lead, by using the nonequilibrium Green's function method. The thermoelectric figure of merit ZT can be evaluated in several different ways, for example, by imposing a condition that the spin accumulation across the system is zero ( Δ μ s = 0 ) or that the spin current is zero ( I s = 0 ). We find that ZT in the case of Δ μ s = 0 is always greater, especially when the spin polarization degree of the ferromagnetic lead is large. Meanwhile, in each case the ZT value drops when the spin polarization degree is increased. Effects of electron interaction on thermoelectric properties are also discussed briefly. [ABSTRACT FROM AUTHOR]

We investigate the structural properties and ionized spin electrons of an Fe–graphene system, in which the time-dependent density functional theory (TDDFT) within the generalized gradient approximation is used. The electron dynamics, including electron ionization and ionized electron spin polarization, is described for Fe atom adsorbed graphene under femtosecond laser irradiation. The theoretical results show that the electron ionization and ionized electron spin polarization are sensitive to the laser parameters, such as the incident angle and the peak intensity. The spin polarization presents the maximum value under certain laser parameters, which may be used as a source of spin-polarized electrons. [ABSTRACT FROM AUTHOR]

• Dwell time is evaluated for electron in the EMEBN device. • Electron spins can be separated in time dimension. • Spin polarization is modulated by properly constructing SM stripe. • A temporal spin splitter is proposed for semiconductor spintronics. We calculate dwell time of electron in magnetically and electrically confined semiconductor nanostructure (MECSN), which can be experimentally fabricated by patterning a ferromagnetic (FM) stripe and a Schottky metal (SM) stripe on top and bottom of InAs/Al x In 1-x As, respectively. Spin-dependent dwell time is found thanks to the Zeeman interaction, which gives rise to the separation of electron spins in time dimension. Properly patterning the SM stripe can obviously improve electron-spin polarization owing to the SM-stripe dependence of effective potential experienced by electron in the MECSN, achieving a tunable temporal spin splitter for semiconductor spintronics device applications. [ABSTRACT FROM AUTHOR]

Based on first-principles method, we construct molecular rectifiers by designing asymmetric hybrid interfacial states. The devices contain a ferromagnetic interface with s p 3 - d hybrid interfacial states and a nonmagnetic interface without hybrid interfacial states. The transport calculation demonstrates that obvious charge-current rectification and spin-current rectification are realized. The analysis of spin-resolved transmission reveals that the asymmetric shift of hybrid interfacial states plays an important role in determining the rectification ratio as well as the spin polarization orientation of the spin current, and hence the form of spin-current rectification. The effect of molecular length is further discussed. A length-induced increase of rectification ratio is observed for the charge-current rectification, while the largest spin-current rectification ratio appears at a specific length. This work demonstrates the potential of hybrid interfacial states in designing excellent molecular spinterface devices. • A molecular rectifier is designed using asymmetric hybrid interface states. • Distinct charge-current and spin-current rectification are realized simultaneously. • Two kinds of spin-current rectification are achieved. • The rectification ratio increases with molecular length. [ABSTRACT FROM AUTHOR]

It is important in spintronics to find high performance materials that can be employ in this field. Based on the density functional theory (DFT), first principles calculations are utilized to inspect the structural, electrical and optical features of half Heusler structure LiCrN. The equilibrium lattice constant is equal to 5.11 Å. The electronic structure results display that the alloy LiCrN shows a half-metallic property. It appears that this structure has semiconductor property with an indirect band gap of 3.65 eV in (PBE-GGA) and 5.06 eV in (HSEO6) in spin down channel and the other spin channel has metallic property. The Cr atom is more effective than the other elements in this material as it carries more valence electrons in outer shell. The spin polarization shows 100% at the Fermi-level. According to Slater–Pauling rule (Z − t 8), the total magnetic moment equals 4 μ B. Additionally, we study the optical properties as we have semiconductor property in one of spin channels so it can be a candidate in optoelectronic devices. The results appear that this structure is promising in spintronics potential applications. • The structural, electronic, magnetic, and optical properties of half Heusler alloy LiCrN are examined. • LiCrN is a half-metal with a magnetic moment of 4 μ B at equilibrium lattice constant 5.11 Å. • The energy gap and the HM gap in the spin-down channel were calculated as 3.65 and 0.5 eV respectively. • The larger contribution of the total magnetic moment is resulting from the Cr atom. [ABSTRACT FROM AUTHOR]

Based on NEGF-DFT computations, systematic investigation of electronic, magnetic and transport properties of AGNRs are done by employing Au through different doping mechanisms. Remarkable Au–AGNR bonding is observed in case of substitution due to the presence of impurity at the edges. Both substitution and adsorption of Au on AGNR surface induce significant changes in the electronic spin transport of the sp 2 hybridized carbon sheets. AGNRs are semiconducting with lower total energy for the FM configuration, and the I–V characteristics reveal semiconductor to metal transition of Au-doped AGNR. The spin injection is voltage controlled in all the investigated Au-doped AGNRs. [ABSTRACT FROM AUTHOR]

The robust effect of curvature on spin polarization is reported in a three-terminal bridge system where the bridging material is subjected to Rashba spin–orbit interaction. The results are examined considering two different geometric configurations, ring- and linear-like, of the material which is coupled to one input and two output leads. Our results exhibit absolute zero spin polarization for the linear sample, while finite polarization is obtained in output leads for the ring-like sample. [ABSTRACT FROM AUTHOR]

We theoretically investigate the electron spin transport properties through a δ -doped magnetic-barrier nanostructure, which can be realized experimentally by depositing two identical ferromagnetic stripes with the opposite in-plane magnetization on the top of a semiconductor heterostructure in parallel configuration and by using atomic layer doping technique. The δ -doping dependent transmission, conductance and spin polarization are calculated exactly by analytically solving Schrödinger equation of the spin electron. It is found that the electronic spin-polarized behavior in this device can be manipulated by changing the weight and/or the position of the δ -doping. Therefore, such a device can be used as a controllable spin filter, which may be helpful for spintronics applications. [ABSTRACT FROM AUTHOR]

We study theoretically the tunneling charge conductance in ferromagnet/spin-triplet superconductor junction with the spin–orbit coupling interface. It is shown the symmetry of the conductance about the relative angle between the magnetization in ferromagnet and the d -vector in superconductor is broken due to the presence of the interfacial Rashba spin–orbit coupling. We present the conductance for various cases of the angle. For each angle, the spin-active mechanism provided by the interface is investigated. The interface effects for different spin polarization in the ferromagnet is also considered. [ABSTRACT FROM AUTHOR]

Based on the dual-gated silicene, we have evaluated theoretically the spin-dependent transport in lateral resonant tunneling structure. By aligning the completely valley-polarized beam with spin-resolved well state in concerned structure, large spin polarization can be expected owing to spin-dependent resonant tunneling mechanism. Under the gate electric field modulation, the forming quantum well state can be externally manipulated, triggering further the emergence of externally-controllable spin polarization. Importantly, integrating the considered structure with a proper valley-filter, which might be constructed from valley-contrasting physics as that in graphene valleytronics, completely-polarized spin beam can also be attained without the assistance of ferromagnetic component, providing thus some profitable strategies to develop nonmagnetic spintronic devices residing on silicene. [ABSTRACT FROM AUTHOR]

We investigate the electronic transport in a silicene-based ferromagnetic metal/ferromagnetic insulator/ferromagnetic metal tunnel junction. The results show that the valley and spin transports are strongly dependent on local application of a vertical electric field and effective magnetization configurations of the ferromagnetic layers. In particular, it is found that the fully valley and spin polarized currents can be realized by tuning the external electric field. Furthermore, we also demonstrate that the tunneling magnetoresistance ratio in such a full magnetic junction of silicene is very sensitive to the electric field modulation. [ABSTRACT FROM AUTHOR]

We calculate conductance and polarization for the laterally asymmetric quantum point contact. We consider both Rashba coupling and spin-orbit interaction induced by asymmetric lateral confinement, without external magnetic field. We show that a conductance plateau may appear at 0.5G0(G0=2e2/h), without Rashba coupling and lateral spin-orbit interaction. For a spin-polarized injected current, the lateral spin-orbit interaction gives additional control of the conductance by varying the side gates potential. For unpolarized electrons, the spin polarization arises along all coordinate axes. There is a possibility of switching of spin polarization by the gates potential. [ABSTRACT FROM AUTHOR]